Yes sound would've made it a lot clearer when something was closing in and from which side. Also there isn't a link between the enemies and song, but they do have a pattern. The way it fits in with the theme was how typically you play the good guy in games but in this you play as the bad guy and you are killing the good guys to stay alive. I probably could've made it fit the theme better by making it so the yellow bats you use one hand and then your other hand for the purple bats, or something like that.
Thanks for playing and the feedback!